Rotorcraft

Crippen maintains a leading research program focused on developing innovative rotorcraft configurations that expand the operational envelope beyond conventional helicopter capabilities. This specialty encompasses the development of compound rotorcraft that combine main rotors with auxiliary propulsion to achieve higher speeds, tiltrotor systems that transition between vertical and horizontal flight, and multirotor configurations optimized for urban air mobility applications. Researchers at Crippen are investigating advanced aerodynamic concepts including slowed rotor systems, variable geometry rotors, and integrated lift-thrust systems that optimize performance across the full flight envelope. The work includes developing comprehensive analytical tools for predicting the aeromechanical behavior of these advanced configurations and validating predictions through wind tunnel testing and flight experiments. The facility's research addresses the complex aerodynamic interactions that occur in compound and tiltrotor systems, including rotor-wing interference, download effects, and transition flight dynamics.

The facility operates a comprehensive research program in electric and hybrid-electric propulsion systems specifically tailored for vertical lift applications, addressing the unique power and energy requirements of rotorcraft operations. This specialty encompasses the development of distributed electric propulsion architectures where multiple electric motors drive individual rotors or propellers, hybrid systems that combine turbine engines with electric motors for improved efficiency, and fully electric systems for short-range urban mobility. Researchers at Crippen are investigating the integration of high-power-density electric motors with rotor systems, advanced battery and fuel cell energy storage systems, and thermal management solutions for high-power electrical components. The work addresses the unique challenges of electric propulsion for rotorcraft including the high power demands of hover, the need for rapid power modulation during maneuvering flight, and the optimization of energy consumption across varying flight profiles. The facility's research includes developing test methodologies for evaluating electric propulsion system performance and reliability in rotorcraft applications.

Crippen maintains extensive capabilities in studying the complex aeromechanical interactions that govern rotorcraft behavior, including the coupling between aerodynamic loads, structural response, and flight dynamics. This specialty encompasses the development of advanced computational models for predicting rotor wake development, blade-vortex interactions, and unsteady aerodynamic phenomena. Researchers at Crippen are investigating aeroelastic stability boundaries including whirl flutter in tiltrotor systems, ground resonance in helicopters, and airframe-rotor coupling effects. The work includes developing active control strategies for suppressing undesirable aeroelastic phenomena and optimizing rotor designs for improved stability margins. The facility's wind tunnel and dynamic test capabilities enable comprehensive validation of analytical models and exploration of aeromechanical phenomena across various operating conditions. The research addresses the challenges of predicting and controlling complex rotorcraft behaviors that arise from the interaction of rotating and non-rotating components.

The facility conducts research focused on reducing rotorcraft noise to enable expanded operations in noise-sensitive environments and improve community acceptance of vertical flight operations. This specialty encompasses the development of advanced rotor blade designs that minimize blade-vortex interaction noise, tip shape optimization for reduced impulsive noise, and operational procedures that minimize noise impact. Researchers at Crippen are investigating active noise control techniques including individual blade control, higher harmonic control, and active trailing-edge devices that modify blade aerodynamics to reduce noise generation. The work includes developing comprehensive noise prediction models that account for atmospheric propagation effects and developing metrics for assessing community noise impact. The facility's anechoic chambers and outdoor acoustic measurement capabilities enable detailed characterization of noise sources and validation of noise reduction concepts. The research addresses the challenge of achieving significant noise reductions while maintaining or improving rotorcraft performance and operational capability.

Crippen maintains an active research program focused on developing autonomous flight capabilities specifically tailored for the unique dynamics and operational requirements of rotorcraft. This specialty encompasses the development of flight control algorithms that handle the complex coupling between rotor dynamics and vehicle motion, trajectory planning systems that account for rotorcraft performance constraints, and decision-making architectures for autonomous operations. Researchers at Crippen are investigating control strategies for handling autorotation and other emergency conditions autonomously, envelope protection systems that prevent entry into dangerous flight regimes, and adaptive control approaches that accommodate changing vehicle dynamics. The work includes developing sensor fusion algorithms that combine inertial, visual, and ranging sensors for precise state estimation in hover and low-speed flight where global navigation satellite system accuracy may be insufficient. The facility's flight simulation and outdoor testing capabilities enable comprehensive validation of autonomous systems across the full range of rotorcraft flight conditions including hover, low-speed maneuvering, and high-speed cruise.